SEMISPINALIS. MULTIFIDUS SVIIS^E. 303 



gissimus ; 7, ilio-costalis drawn slightly inwards to show the slips of insertion into the 

 lumbar fascia and the various ribs ; inside the costal insertions are seen the origins of the 

 •accessorius ; 7', the asceudeus cervicis continued upwards from the aceessorius ; 8, spinalis 

 ■doisi. On the right side, 6, marks, in the lumbar region, the insertions of the loncis- 

 ^imus dorsi into the upper four transverse processes (the insertion into the accessory pro- 

 cesses not being shown) ; in the dorsal region the narrower tendons of insertion into the 

 lower part of the dorsal transverse 25rocesses (the six lower only are represented) ; 6', the 

 series of insertions into nine ribs ; 7, the ilio-costalis drawn outwards ; 7', placed between 

 the lowest costal insertion of the ilio-costalis and the lowest origin of the accessorius ; 

 7", extension of the ascendens cervicis from the fifth rib towards the neck ; 9, 9, semi- 

 spinalis colli; 10, 10, semi-spinalis dorsi ; 11, 11, lower dorsal and lumbar parts of 

 the multifidus spinte, which appears again above the semi-spinalis colli, over the upper 

 9 ; 12, levatores costarum, long and short ; 13, in the upper part of the figure, points 

 by four lines to the rectus capitis posticus minor, i-ectus major, obliquus superior, and 

 ■obliquus inferior muscles. 



Hclnfions. — The complexus muscle is covered by the splenius, except at its 

 lowest origins from the dorsal vertebra and at the internal portion of its upper 

 ■extremity ; the trachelo-mastoid and transversalis cervicis rest upon its series of 

 origins, and the semispinalis colli, the posterior recti, and the obliqui capitis, 

 together with the deep cervical artery, are concealed by it. 



The semispinalis muscle consists of fibres extending from trans- 

 verse processes to spines, each bundle crossing over about five vertebra. 

 It is described in two parts. 



a. The semispinalis colli is the part under cover of the complexus. 

 It arises from the internal tubercles of the upper four or five dorsal 

 transverse processes, and is inserted into the spines of the cervical 

 vertebraj from the second to the fifth inclusive being thickest at its 

 insertion into the second yertebra. 



h. The semispinalis dorsi, not covered by the complexus, consists of 

 narrow muscular bundles interposed between tendons of considerable 

 length, and forms an elongated thin stratum, especially towards its 

 lower border. It arises from the transverse processes of the dorsal 

 vertebras from the tenth to the fifth inclusive, and is inserted into the 

 spines of the last two cervical and first four dorsal vertebrte. 



The multifidus spinas muscle reaches from the sacrum to the axis 

 vertebra, passing up under cover of the semispinalis, and is much more 

 largely developed towards the lower than at the upper end of the 

 column. In the sacral region the fibres arise from the deep surface of 

 the tendinous origin of the erector spina, from the groove on the back 

 •of the sacrum as low as the fourth foramen, from the inner part of the 

 posterior extremity of the iliac crest, and from the ligaments between 

 that bone and the sacrum ; in the lumbar region they take origin from 

 the mammillary processes ; in the dorsal region from the transverse 

 processes ; and in the neck from the articular processes of the four 

 lower cervical vertebra. From these several points the muscular 

 bundles ascend obliquely, to be inserted into the laminiB of the vertebra, 

 and into the spines from their bases nearly to their extremities. The 

 fibres from each point of origin are fixed to several vertebra?, some 

 being inserted into the side of the spinous process next above, and 

 others ascending more and more vertically as high as the fourth from 

 the place of origin ; the longer fibres from one origin overlapping those 

 from the origin next above. 



The rotatores spinas are eleven pairs of small muscles, which may 

 be regarded as the deepest fibres of the multifidus spiniB in the dorsal 



